Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/06—Suspending or supporting devices for articles to be coated
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/001—Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/004—Sealing devices
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/005—Contacting devices
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D7/00—Electroplating characterised by the article coated
  • C25D7/12—Semiconductors
  • C25D7/123—Semiconductors first coated with a seed layer or a conductive layer
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/22—Secondary treatment of printed circuits
  • H05K3/24—Reinforcing the conductive pattern
  • H05K3/241—Reinforcing the conductive pattern characterised by the electroplating method; means therefor, e.g. baths or apparatus

Definitions

• the invention relates to a device and a method for comparing the thickness of metal layers at electrical contact points on flat items to be treated, such as conductor foils and printed circuit boards, in the electrolytic treatment, in particular electrolytic metallization, of the items to be treated, which are guided in a horizontal transport plane in a continuous galvanizing system.
• the device is used in systems in which the material to be treated is guided in a horizontal position.
• flat items to be treated are usually gripped on one or both sides of the edge of clamps or clamps.
• the clamps or clamps serve to transport the material to be treated through the system and at the same time to make electrical contact, i.e. for supplying the electroplating current to the good.
• the items to be treated are, for example, printed circuit boards, in particular so-called multilayers (multilayer circuits), with board thicknesses of up to 8 mm. It happens that such a thick plate as well as foils with a thickness of only 0.1 mm or less are produced in a continuous galvanizing plant.
• Another requirement for an electroplating system is the required uniformity and accuracy of the distribution of the metal layer thickness.
• the electrolytically deposited metal layers have to be very uniformly thick down to the edges of the material to be treated.
• the edge areas in which there are significant deviations from the specified standard layer thickness should be as narrow as possible.
• a relative layer thickness tolerance is used, for example. required in the usable area of the material to be treated (outside the unusable marginal area), which is below 10 percent.
• the required uniform layer thickness distribution cannot be achieved even in the vicinity of the points on the material to be treated, at which the clamps or clamps attach during the galvanization. Therefore, the areas near these contact points are added to the peripheral areas.
• the material to be treated is gripped by the clamps on the side edge of the inlet of the electroplating system.
• two brackets are pivoted against each other and the edge of the material to be treated is held in the clamp by means of a compression spring.
• to open the clip it is proposed to move the brackets perpendicular to one another. In this case, the contact force is applied by a tension spring.
• the clips are opened again by means of an inclined contact surface. The circuit boards are then released again and are usually transported further by transport rollers.
• the metal clips of the clips are also metallized. These thus act as predatory cathodes in relation to the surface of the material to be treated, which is in the vicinity of the clamps. Because of the lower layer thickness that occurs in this area, a correspondingly wide edge strip cannot be used. Experience has shown that this unusable width is approximately 60 mm. In order to avoid the formation of layer thickness fluctuations, it is recommended in the cited document to provide the brackets with a plastic covering. Only the ends that make contact with the material to be treated should then remain shiny metallic. The publication also states that these points are electrolytically demetallized again in a demetallization chamber when the clips return in the system.
• the plastic cover enables the clamps to be operated within the Electrolyte bath. Additional sealing walls to keep the electrolyte away from the clips are therefore not necessary. This operating mode is referred to below as wet contacting.
• the plastic covering of the brackets consists, for example, of ECTFE (poly (ethylene-trichlorofluoroethylene)). The production of a plastic cover with this chemically resistant plastic is very complex and therefore expensive.
• the brackets are polarized during electroplating.
• the plastic covering of many staples becomes metallized after a long period of use.
• the undesired metallization takes place even if the clips are regularly electrolytically demetallized in the return.
• the reasons for this are not known.
• the aging of the plastic coating in connection with the organic and / or inorganic electrolyte additives presumably plays a role in this: the firmly adhering metallic layer on the plastic coating begins to grow in the electrolyte from bare metal parts of the clips, for example the bare contact points at the ends the coat hanger.
• these are also damage to the plastic coverings of the clamps, which are caused by cleaning work during rough operation, for example by incorrectly positioned and very sharp-edged printed circuit boards or by improper handling of the coverings.
• the clip If the clip is again in the metallization area of the electroplating system, the remaining metallization becomes electrically conductive again due to the damaged area by electrolytically depositing new metal within the damaged area via the electrical connection to the metal bracket.
• the metallization therefore continues to grow. This repetitive, slow process leads to the clips being unusable after weeks or months in a system that is in continuous operation, since the undesired metallization on the plastic casing acts as a predatory cathode compared to the metallization on the material to be treated.
• the plastic cover must therefore be replaced. This is associated with high costs. In addition, there is a loss of production.
• DE 32 36 545 C3 describes a device for electroplating individual, plate-shaped workpieces which are successively guided in a horizontally directed movement by means of rotatable conveying devices through an electrolytic bath provided with seals on the inlet and outlet sides, with the conveying device in the bath and in particular a plurality of cathodically connected, paired opposing contact wheels which can be pressed against one another is also provided for the electrical contacting of the workpieces on one side of the conveying path.
• the contact wheels are provided with covers which have appropriately slotted openings for the passage of the workpieces, wiping devices being provided along the slotted openings of the covers and being carried in front of the covers which abut on the workpieces to limit the contact of the contact wheels with the electrolytic liquid.
• EP 0 254 962 A1 describes contact terminals which are provided for dry contacting.
• the contact terminals are shielded from the access to the electrolyte solution by means of a seal which is in contact with the material to be treated.
• the other, non-contacting areas of the contact terminals are covered with plastic to protect them against undesired metal deposition. Unwanted deposits on the contact terminals are removed by chemical and / or mechanical cleaning in the return of the terminals. Sealing the cathode clamps by means of a seal that rests on the material to be treated under spring pressure leads to disadvantages because printed circuit boards are always sharp-edged.
• the invention is therefore based on the problem of avoiding the disadvantages of the known devices and methods and, in particular, of specifying a device which can be produced inexpensively and which enables largely maintenance-free continuous operation. Above all, it should be possible to obtain a uniform layer thickness distribution on the material to be treated and in its holes, both in the case of thick printed circuit boards and in the case of thin conductor foils, which can also be achieved in the edge region of the material to be treated without having to retrofit the system.
• the device according to the invention and the method serve to even out the thickness of metal layers at electrical contact points during the electrolytic treatment of the material to be treated.
• the device contains counter electrodes opposite the transport plane and clamps attached to an endlessly rotating transport means for contacting the material to be treated.
• the clamps each have a lower clamp part and an upper clamp part, which are electrically conductive, on the surface
• Metal are movable relative to each other and each have at least one contact point for the material to be treated. Furthermore, at least one current source is provided for generating a current flow between the counter electrodes and the clamps. Between the counter electrodes and the clamps, upper and lower shields for the electric field are arranged, which come so close to the transport plane that the material to be treated and the clamp parts in the transport plane cannot just be touched by the shields.
• the device and the method are used in particular in the electrolytic treatment of printed circuit boards and printed films, which are guided and treated in a horizontal transport plane in a continuous galvanizing system.
• the thickness of the metal layers is evened out particularly in the case of the electrolytic metallization (galvanization) of the material to be treated.
• the device and the method can also be used in the electrolytic demetallization or in the electrolytic etching of metal layers.
• the following explanations relate exclusively to the electrolytic metallization of the material to be treated; however, the explanations apply mutatis mutandis to the demetallization or the etching of the metal layer on the material to be treated.
• the counter electrodes in this case are connected as cathodes and the material to be treated is anode, while in the case of galvanizing the material to be treated
• Counter electrodes as anodes and the material to be treated as a cathode can also be connected to a pulse current or pulse voltage source, for example for generating mono- or bipolar pulse currents between the counter electrodes and the items to be treated.
• the counter electrodes are briefly poled one after the other anodically and cathodically and the material to be treated is reversed.
• both clamp parts are shielded against the anodes (counter electrodes), which can be both soluble and insoluble.
• One of the shields is located in the space between the lower anodes of the electroplating system and the clamp lower parts.
• the other shield is in the space between the top anodes and the top clamps.
• the shields are preferably essentially flat and are oriented essentially perpendicular to the transport plane and parallel to the transport direction of the material to be treated in the electroplating system.
• the shields are preferably made of an electrically non-conductive material, such as plastic or ceramic. However, they can also consist of an electrically conductive material which is provided on the surface with an insulating coating or with an anodic passivation layer, for example of insulating-coated metal or of a metal anodically passivated on the surface, such as titanium.
• the metal can be connected to the respective upper or lower anode potential in order to avoid possible intermediate conductor electroplating.
• electrically conductive connections between the shields made of electrically conductive material and the anodes are provided.
• This electrically conductive connection between the shields and the anodes can have an electrical resistance for safety reasons.
• a short-circuit current limiting resistor can be inserted.
• the shields extend along the entire transport route in the electroplating area of the continuous system. To avoid a short circuit, electrically conductive shields are attached in such a way that the clips and the material to be treated do not touch each other in undisturbed continuous operation. The shields from an insulator are also adjusted so that experience shows that gradual galvanization is possible so that they do not touch the surface of the material to be treated or the clamp parts.
• the shields against electrolyte solution flowing through are not completely sealed.
• the bare clamp parts are therefore also slightly galvanized in the area of the clamp gripping point, ie in the area of the material to be treated.
• the influence of this metal deposition on the layer thickness distribution of the printed circuit boards in the area of the clamp gripping points is slight. In practice, this means that only a narrow edge strip of the printed circuit boards is technically unusable. It is important for the reproducibility of precise electroplating results in continuous systems that in the area of the gripping points, slightly metallized clips are completely electrolytically demetallized and cleaned with each return. Since the clips are not covered with plastic, each metal deposit on the clips has an ideal electrically conductive connection to the demetallization power source.
• the complete absence of a plastic covering of the clip parts is also advantageous in terms of the cost and the service life of the clips.
• the bare clamp is inexpensive to manufacture, and the service life is almost unlimited.
• the lower half of the bracket with its contact point is always at the constant level of the lower sides of the printed circuit boards in the transport plane.
• the lower shield can therefore be guided very precisely to the underside of the circuit board. With an achievable distance of the shield to the underside of the printed circuit board and to the lower part of the clamp of approximately 1 mm each, an almost complete shielding of the electrical field can be realized at the location of the lower part of the clamp.
• the upper clamp parts are designed to be displaceable.
• the upper shielding must therefore be arranged so far away from the top of the circuit board that there is also a safety distance of about 1 mm from the top of the circuit board to the shield for the thickest circuit boards to be transported. This means that with a maximum PCB thickness of 8 mm, the distance between the upper shield and the zero level (level of the underside of the PCB) must be 9 mm. Because of this relatively large distance, metal is deposited on the upper part of the clamp to a not inconsiderable extent when processing foils with a thickness of, for example, 0.1 mm.
• the unusable edge area of the circuit boards decreases due to the increasing shielding. If printed foils or printed circuit boards with only slight differences in thickness or only with a single thickness are produced in a galvanizing system, the upper shielding can also be adjusted very precisely to the thickness of the material to be treated. In practice, this case of mono production occurs predominantly. The unusable edge area of the material to be treated is minimal in this case.
• each bare metal upper part of the clamp is equipped with a moving cover , which is attached to the upper part of the bracket.
• the diaphragm is aligned essentially parallel to the upper part of the clamp and extends so close to the transport plane in which the printed circuit boards or foils are guided that the diaphragms can barely touch the material being treated in the transport plane and the contact point.
• the panel consists of an electrically non-conductive material, such as
• Example ceramic or plastic It is attached to the upper part of the clamp at a greater distance from the clamp contact point. There is almost no electrical field at the attachment point due to the upper shielding. This prevents the application of a metallic layer on the plastic.
• the panel extends from the attachment point to the contact point. Due to the attachment to the upper part of the clip, it performs all opening and closing movements of the upper part of the clip.
• the distance of the screen to the top of the items to be treated is set as well as that of the lower shield to the bottom of the items to be treated. The screen therefore does not touch the surface of the material to be treated and also the contact point of the clamp.
• the width of the diaphragms corresponds approximately to the distance from one clip to the adjacent clip.
• the static shield described is arranged between the screens and the upper anode baskets with the required collision-avoiding distance. With the additional panels, the technically unusable edge strip of a treatment item in the clamp area is reduced to 12 millimeters. This strip width is independent of the thickness of the goods and always the same size.
• substantially horizontally oriented upper diaphragms and on the lower shields substantially horizontally oriented lower diaphragms can be attached to the diaphragms or to the upper shields. These serve to further even out the layer thickness distribution in the edge region of the material to be treated, since the electrical field lines generally concentrate in edge regions of electrically conductive objects and lead there to higher metal layer thicknesses. To further advantageously influence the distribution of the metal layer thickness on the material to be treated, openings are also provided in the horizontally oriented panels.
• the contact points on the upper and lower clamp parts for the electrical contacting of the material to be treated are preferably arranged on the outermost ends of the clamp parts.
• Figure 1 a a section of a schematic cross-sectional view through a horizontal continuous electroplating system, seen in the direction of transport, with shields and with a clip gripping a film;
• Figure 1 b a cross-sectional view of a large circuit board
• Thick gripping bracket Figure 2a: a view as in Figure 1a of the system with a clip with an additional panel; Figure 2b: a view as in Figure 1 b of the system with a bracket with additional cover;
• Figure 3 a front view of attached to the upper bracket
• Figure 4 is a view as in Figure 1 b of the system with a bracket with additional horizontal panels;
• Figure 5 a schematic cross section through the upper region of a horizontal continuous plating system according to the prior art.
• a conventional electroplating system is shown in Figure 5.
• the working container 1 there are upper anode baskets 2 and lower anode baskets 3.
• a real six-meter-long continuous galvanizing system consists, for example, of twenty-five upper and twenty-five lower anode baskets. These are arranged one behind the other in the transport direction of the material to be treated, for example printed circuit boards. In the view in FIG. 1, seen in the transport direction, only an upper and a lower anode basket can therefore be seen.
• the brackets 4 lie one behind the other in the figure.
• the distance from clamp to clamp is, for example, 60 mm.
• the clips 4 are attached to a motor-driven endless conveyor belt 5.
• the clamps 4 grip the material to be treated 7 at the chamber contact point 6 (section Z).
• the working container 1 is filled with electrolyte.
• the bath level 8 lies above the upper anode baskets 2.
• the electroplating area 9 In the right part of FIG. 1 there is the electroplating area 9 and in the left part the demetallization area 10. The same electrolyte liquid is in both areas.
• the anodes, here in the form of baskets 2, 3, are filled with soluble anode metal.
• the anodes 2, 3 and the material to be treated 7 together form the electroplating cells.
• the clips 4 and the cathodes 11 in the demetallization region together form the demetallization cell.
• the potentials of all electrodes are also shown in FIG. 5.
• the cathode potential for the metallization is applied via the sliding rail 32 to the clamps 4 and from there to the material to be treated 7 via sliding contacts 31.
• the anode potential for the demetallization is applied to the clips 4 to be demetallized in the demetallization region 9 via further sliding contacts 33.
• the clips 4 are covered with a plastic covering 12 far beyond the bath level 8 (section Z). Only the clamp contact points 6 are bare metal. These are electroplated in the electroplating area 9 as well as the material to be treated 7. Furthermore, the clamp plastic sheathing is electroplated here, as described above.
• the clamp contact points 6 are demetallized again in the demetallization region 10. By contrast, the metal layer on the plastic sheath is only partially removed by demetallization. After a long period of operation, this leads to the unusability of these known clips.
• the arrangement according to the invention shown in FIGS. 1 a and 1 b serves to avoid this failure.
• the brackets 4 consist of bright metallic material, for example titanium. So there is no need for a plastic cover. These clamps grip the material to be treated 7 and guide it through the electroplating area 9 of the continuous electroplating system.
• an upper shield 15 is inserted between the upper anode basket 2 and the clamp 4.
• a lower shield 16 is inserted below the material to be treated in the electrical field leading from the lower anode basket to the lower clamp part 14.
• the shields 15, 16 extend along the entire transport path in the electroplating area 9 of the electroplating system.
• the lower shield 16 extends close to the surface of the material to be treated.
• the level of the underside of the material to be treated is predetermined by the driven support rollers 17 and is therefore constant.
• the safety distance 18 between the upper end of the shield 16 and the lower surface of the material to be treated can thus also be kept constant and small.
• the axis of the support rollers 17 is guided through a hole in the lower shield 16. The axis can also be mounted in this shield.
• the upper distance 19 between the lower end of the shield 15 and the upper surface of the material to be treated must be chosen so large that the safety distance for the material to be produced with the greatest thickness 20 a value is also maintained which corresponds to the lower distance 18. This situation is shown in detail in Figure 1 b.
• Electric field lines of the electric field of the upper anode reach through the gap 19 between the lower end of the upper shield 15 and the material to be treated 7 and meet the lower region of the clamp 4 if there is a greater distance due to the processing of thin foils.
• the result is a distance-related galvanization of an area 21 on the bare metal bracket.
• the diaphragm 22 shown in FIGS. 2a and 2b is attached to the upper clamp part 13.
• the aperture 22 consists of an electrically non-conductive material. It does not touch the clip in the lower area. This prevents the plastic of the screen from possibly being galvanized, as described above.
• the attachment point 23 on the upper clamp part 13 should be positioned so that the electrolyte path from the point to the upper anode basket 2 is as long as possible in order to avoid metallization of the screen 22 in the long term.
• the attachment point 23 can be below or above the bathroom mirror. If it lies below the bath level, the field lines which start from the anode are kept away from the fastening point 23 by the upper shield 15. In this way, the possible growth of an electroplating layer from the bare metal upper part 13 of the bracket 22 is reliably avoided even when the fastening point and thus the bracket are located below the bath level 8.
• Layer thickness distribution on both sides of the material to be treated is achieved right into the edge area.
• brackets are bright metallic and not with a plastic insulation tion are provided, there is a more advantageous embodiment of the clamp contact points.
• the isolated projections 24 in FIG. 5 above the clamp contact points 6 are completely eliminated here.
• the clip contact points are located at the outer end of the clip parts (in the direction of the usable area of the item to be treated 7), so that the shielding effect of the clips on the item to be treated is further minimized.
• the unusable edge of the clamp reaches a minimum in particular if at the same time the shields 15, 16 and the screen 22 are made very thin in the vicinity of the material to be treated;
• the shielding made of a passivated or coated metal is particularly suitable for this.
• brackets with attached panels 22 are shown in the front view without material to be treated, for example circuit boards.
• the view shows a section of the system in side view, i.e. the direction of transport for the material to be treated runs from left to right or from right to left in the figure. Since no material to be treated is shown, the upper clamp parts and the lower clamp parts touch one another at the contact points.
• the diaphragms have a width 35.
• the lower clamp contact point 6 is shielded by the lower fixed shield 16.
• a diaphragm gap 25 is formed between two diaphragms 22 on adjacent staples. This should be as small as possible in order to avoid galvanizing the staples. In an embodiment not shown, the diaphragms 22 can also overlap one another. This closes the gap.
• the layer thickness distribution of the material to be treated should adhere to a predetermined tolerance except for a narrow edge area of the material to be treated. It is known that a field line concentration occurs in the edge region of the material to be treated.
• the bare metal clamp represents only a weakly acting predatory cathode through the safety distances between the shields or the screen and the treatment material surfaces. The consequence of this is an increase in the layer thickness on the treatment material in the vicinity of the screen 22 and the shields 15, 16.
• the lower panel 27 can be mounted continuously in the transport direction. At the top, the length of the traveling panels 22 corresponds to the distance between brackets plus a possible overlap of the panels.
• the apertures 26, 27 are preferably provided with openings 30.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Sustainable Development (AREA)
• Life Sciences & Earth Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Electroplating Methods And Accessories (AREA)
• Control Of Metal Rolling (AREA)
• Manufacturing Of Printed Wiring (AREA)
• Manufacture Of Switches (AREA)

Applications Claiming Priority (3)

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• 1997
  • 1997-08-21 DE DE19736352A patent/DE19736352C1/de not_active Expired - Fee Related
• 1998
  • 1998-08-03 TW TW087112726A patent/TW420727B/zh not_active IP Right Cessation
  • 1998-08-19 DE DE59803992T patent/DE59803992D1/de not_active Expired - Lifetime
  • 1998-08-19 US US09/485,785 patent/US6319383B1/en not_active Expired - Fee Related
  • 1998-08-19 WO PCT/DE1998/002503 patent/WO1999010568A2/fr active IP Right Grant
  • 1998-08-19 EP EP98951219A patent/EP1007766B1/fr not_active Expired - Lifetime
  • 1998-08-19 CA CA002301315A patent/CA2301315A1/fr not_active Abandoned
  • 1998-08-19 KR KR10-2000-7001776A patent/KR100535198B1/ko not_active IP Right Cessation
  • 1998-08-19 BR BR9811978-8A patent/BR9811978A/pt not_active Application Discontinuation
  • 1998-08-19 AT AT98951219T patent/ATE217036T1/de not_active IP Right Cessation
  • 1998-08-19 CN CNB988082500A patent/CN1158412C/zh not_active Expired - Lifetime
  • 1998-08-19 JP JP2000507870A patent/JP4194238B2/ja not_active Expired - Lifetime
• 1999
  • 1999-07-13 KR KR1020017001804A patent/KR100626130B1/ko not_active IP Right Cessation
  • 1999-07-13 US US09/762,759 patent/US6887113B1/en not_active Expired - Lifetime

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